1. Field of Invention
The present invention relates to Internet Protocol telephony, and more particularly to a method for handling the signaling related to the storing and forwarding of voice and video messages in an Internet Protocol based network.
2. Description of the Related Art
Internet Protocol (IP) telephony is the real time delivery of voice, and other multimedia data, between two or more parties across a network using Internet protocols. Internet telephony began in the mid-1990's with PC-to-PC Internet telephony, which required both parties to have a personal computer with specialized hardware and software, allowing voice signals to be transmitted over the Internet. More recently, IP telephony systems have been suggested which utilize the existing public switched telephone network (PSTN) infrastructure integrated with IP networks, such as the Internet.
Internet technology is session based, rather than connection based. An Internet protocol, such as Session Initiation Protocols (SIP) is typically used to establish the session and negotiate the capabilities for the session. Once the session is established, the actual media is transported across the IP network using a different protocol, such as Real-time Transport Protocol (RTP). IP telephony use has advanced rapidly since its introduction.
IP telephony has advantages over the PSTN, providing a cost savings for both users and carriers while allowing the transport of a variety of media types, such as voice and video, as opposed to just voice as in the case of the PSTN. While IP telephony may someday replace the PSTN, it suffers some disadvantages in that it currently lacks many of the features already developed for the PSTN. One such feature is call message deposit and retrieval.
The SIP protocol is currently a leading protocol for establishing IP telephony sessions. However, currently no definitions have been established in the SIP protocol to handle the call forwarding logic and signaling requirements necessary for proper interfacing with messaging systems for message deposit and retrieval. The conditional forwarding of calls for deposit in a messaging system is generally done when a called party is either busy or fails to answer a call. A called party may also wish to have a caller unconditionally deposit a message in a messaging system. In either case, the messaging system interface must provide signaling capabilities to store the message, whether conditionally or unconditionally, and also for a called party to later retrieve the deposited message. The signaling capabilities must also include information about the calling party depositing the message. The identity of the called party must also be verified when he or she retrieves the deposited message.
Therefore, a need exists for a method of handling the signaling required for IP telephony voice and video message deposit and retrieval in an IP based network using the SIP protocol, thereby allowing integration of the IP network with an Integrated Messaging System (IMS).